risk category (IBC 1604.5) vs seismic use groups (1616.2)

[arianelourieharrison]

I am getting confused by when to use the occupancy categories (Table 1604.5) which has 4 categories, essential facilities listed as category IV and seismic use groups (Table 1616.2) with 3 use groups, essential facilities listed as group III. In Ching's illustrated IBC (p 297) it is written that group III, essential facilities, is the same as Category III (1604.5) which he lists as essential facilities. on table 1604.5 IBC III is actually substantial hazard...can anyone clear this up for me? what is the real class III here?

[Mike-SE]

Hopefully I can clear this up.
1. IBC 2006 is the code referenced by the exam
2.IBC 2006 has no section 1616.2
3. IBC 2006 does not reference seismic use group, rather it references occupancy categories
Seismic use group was contained in earlier versions of IBC but no longer used.
Please read by seismic guides, they do not explicitly answer your questions. But they do tell you what is in IBC 2006

[arianelourieharrison]

thank you Mike, IBC 2006 it is. I will reread your notes..

[anonymous283]

If IBC is the code referenced by the exam then why is the 1616.2 referenced in the are 3.1 lateral forces questions? I got that question wrong thinking it was the IBC way - why on earth are there 2 of these groups?!